[Elecraft] Issues with KPA100 (K2/10 is 100% OK)

[dl9hda at dl9hda.de]

Hi,

my K2 works well but I have issues with my KPA100. KPA100 and KAT100 are 
both situated in an external enclosure but the KAT100 is permanently 
disabled (cal-mode). I used the KPA100 to drive my tube-amplifier ...

I cannot exactly say what happend but for a year or so the maximum 
output power on all bands has been only 60W. It's enough for the tube-pa 
but now the output is zero.

If I change the band or hit the antenna-switch the relays are working. 
So the communication seems to be OK.

While pressing tune the K2 says high current and there is absolutely no 
output-power an the K2 and of course at the KPA100. (The K2 without any 
connections to the second enclosure works pretty well!!!).

So the first guess was to check the diodes D16 and D17. I did not 
desolder them but I made some measurements with mit Fluke 177.

D16: Diode-Voltage zero and the other direction shows 0.390 V. The 
resistor-values are 95.7 KOhms and 104,6 KOhms
D17: Diode-Voltage zero and the other direction shows 0.387 V. The 
resistor-values are 95.5 KOhms and 105,2 KOhms




Not so bad I think but what might be the problem? Any hints?


Best regards

Holger, DL9HDA